Hackers Hit Ex-Military Head

The Federal Bureau of Investigation is pursuing foreign hackers who targeted the computers of retired Adm. Mike Mullen, the former chairman of the Joint Chiefs of Staff, in the latest example of what current and former officials call a pattern of attacks on computers of former high-ranking U.S. officials.

The hackers targeted Mr. Mullen's personal computers, which he used while working on the grounds of the U.S. Naval Academy since his retirement in 2011, according to officials and others familiar with the probe. Those...